Electro-pneumatic switch



Nov. 24, 1970 F. E. ERICKSON ELECTRO-PNEUMATIC SWITCH 3 Sheets-Sheet 1Filed Sept. 5, 1968 2 0 M I 4 4 I 6 Q5 0 Q l I 7 6 ME w 4 1 3| 0 v v3 Dv m r 0 9 I44 CONTROL FIG. 5

- INVENTOR.

FREDERICK E. ERICKSON Maya, 746m 8 80;

ATTORNEYS F. E. ERICKSON ELECTRO-PNEUMATIC SWITCH Nov. 24, 1970 3Sheets-Sheet. 2

Filed Sept. 3. 1968 INVENTOR. FREDERICK E. ERICKSON ||||||||.l..|||.lllllllllllll ll.

ATTOR N EYS NOV. 24, 1970 ERlCKSON 3,542,983

ELECTRO-PNEUMATIC SWITCH Filed Sept. 5, 1968 3 Sheets-Sheet 3 INVENTOR.FREDERICK E. ERICKSON ATTORNEYS BY M 114%, g M,

US. Cl. 20061.86 5 Claims ABSTRACT OF THE DISCLOSURE Anelectro-pneumatic switch includes a housing mounting, a fixed electricalcontact and a movable switch arm. A fluid conduit is attached to thehousing in a fixed position and has an outlet opening positionedadjacent the switch arm. The outlet opening of the fluid conduit definesa valve seat and a valve member is positioned between the switch arm andthe valve seat. An actuating member on the housing moves the switch armfrom a position in engagement with the fixed electrical contact to aposition out of engagement with the fixed contact. In theout-of-engagement position, the valve member is biased against the valveseat by the switch arm to close the outlet opening. The switch arm maybe biased to one position by an over-center snap-acting springarrangement.

BACKGROUND OF THE INVENTION This application pertains to the art ofelectro-pneumatic switching devices, and more particularly, to suchdevices which are selectively operable to open or close an electricalcircuit while simultaneously opening and closing the outlet of a fluidconduit. The invention is particularly applicable to controllingbi-stable fluid amplifiers and will be described with particularreference thereto, although it will be appreciated that the inventionhas broader applications and could be used in any electropneumaticcontrol system.

An electro-pneumatic switching device includes features of both anelectrical switch and a pneumatic valve. It is desirable to combinefeatures of both devices so that part of the movable members in theelectrical switch also serve as components of the pneumatic valve. It isalso desirable to rapidly open and close the pneumatic valve to providepositive operation of other devices in the pneumatic system. Inaddition, it is desirable to accurately predict the sequential operationof both the electrical switch and the pneumatic valve. Prior deviceswhich combined pneumatic valves with electrical switches have been soarranged that it is diflicult to predict whether the electrical circuitwill be made or broken before the pneumatic circuit is opened or closed.In addition, prior devices have been rather slow acting as far asopening and closing the pneumatic valve is concerned. Other prior artarrangements have required movement of a pneumatic tube in order to openand close the valve. It would be desirable to have movement of theelectrical switch arm itself actuate the pneumatic valve. In a morelimited aspect, it would be desirable to have no movement of thepneumatic tube when it connects to an electrical switch housing and toarrange the valving inside of the switch housing so that space isconserved and exterior movable parts are minimized.

SUMMARY OF THE INVENTION The present invention contemplates a new andimproved electro-pneumatic switching device which overcomes previousproblems and provides a new arrangement which is far simpler, both inoperation and manufacture, and also very compact, by having no movablepneumatic valve parts exterior of the switch housing. In

United States Patent 0 accordance with the present invention, there isprovided an electro-pneumatic switching device in which a snap actingelectrical switch arm operates to open and close a pneumatic valve, aswell as making and breaking an electrical circuit. More specifically,the present invention includes a conventional switch housing enclosing asnapacting switch arm which cooperates with a fixed electrical contact.A fluid conduit having an outlet opening is positioned in the housingadjacent the switch arm and the switch arm cooperates with the conduitto open and close the outlet opening. In a more limited aspect, a fluidconduit is secured to the housing in a stationary position and the fluidconduit has an outlet opening inside of the housing positioned adjacentthe switch arm. The switch arm cooperates with valve means toselectively open and close the outlet opening as the switch arm movesbetween two positions. In accordance with a still further limited aspectof the invention, an electro-pneumatic switching device is mounted to atimer assembly which is releasably mounted in an enclosure. Theenclosure and the timer assembly include an automatic fluid coupling sothat the pneumatic conduit to the electropneumatic switch isautomatically made and broken as the timer assembly is received in, orremoved from, the timer enclosure.

It is a principal object of the present invention to provide anelectro-pneumatic switching device which is very simple to operate andmanufacture.

It is a further object of this invention to provide such a device whichutilizes movement of a snap-acting electrical switch arm to open andclose a pneumatic valve.

It is another object of the present invention to provide such a devicein a manner that leaves no movable valve parts exterior of the switchhousing.

It is an additional object of the present invention to provide such adevice wherein a fluid conduit is secured to the switch housing in astationary position so that there is no movement of the conduit itselfwhen the valve is operated.

It is also an object of the present invention to provide such a devicein which rapid sequential operation of the electrical contacts and thepneumatic valve is accurately predictable.

BRIEF DESCRIPTION OF THE DRAWING The invention may take physical form incertain parts and arrangements of parts, a preferred embodiment of whichwill be described in detail in this specification and illustrated in theaccompanying drawing which form a part hereof.

FIG. 1 is a schematic diagram showing the electropneumatic switchingdevice of the present invention connected in a fluidic circuit and withthe device itself shown in a side elevational view without a cover;

FIG. 2 is a side elevational view of a timer assembly and timerenclosure with which the present invention is usable and with portionscut away for clarity;

FIG. 3 is a rear elevational view of a timer assembly taken in thedirection of arrows 33 of FIG. 2;

FIG. 4 is a rear elevational view of a timer assembly enclosure taken inthe direction of arrows 4-4 of FIG.

FIG. 5 is a side elevational view of the timer assembly and timerenclosure of FIG. 2 in assembled position and with portions cut away forclarity;

FIG. 6 is a partial side elevational cross-sectional view of a modifiedvalve arrangement;

FIG. 7 is a partial side elevational cross-sectional view of anothermodified valve arrangement;

FIG. 8 is a partial side elevational cross-sectional view taken in thedirection of arrows 8-8 of FIG. 2;

FIG. 9 is a partial elevational cross-sectional view taken in thedirection of arrows 99 of FIG. 2; and

FIG. 10 is a side view of the electro-pneumatic switching device of FIG.1 in its alternate, valve closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,wherein the showings are for purposes of illustrating the preferredembodiment of the invention only and not for purposes of limiting same,FIG. 1 shows electro-pneumatic switch device A connected in a fluidiccircuit with bi-stable fluid amplifier B. The snap-acting switch itselfmay take many forms and many of them are known to those skilled in theart as miniature switches. The switch itself and its specificarrangement for providing snap action may take many forms which are wellknown in the art. Only one of such mechanisms will be described in somedetail as an example of one such snap-acting mechanism.

Electro-pneumatic switching device A includes a housing 12 having anupstanding peripheral wall 14 defining a central recess cavity 16. Wall14 of housing 12 has a groove 17 and recess 18 formed therein. A flatand elongated electrical lead C has end legs 20 and 22, and anintermediate portion 24. Leg 22 is received in recess 18 andintermediate portion 24 is received in groove 17 to fix lead C againstmovement relative to housing 12. Leg 20 may have an electrical wire 26connected thereto as by solder at 28. The flat upper surface 30 ofintermediate portion 24 of lead C has an electrical contact 32 securedthereto in a well known manner.

Wall 14 of housing 12 has another groove 34 and recess 36 formed thereinto respectively receive intermediate portion 38 and the end portion ofleg 40 of electrical lead D which has another leg 42 connected to anelectrical wire 44 as by solder at 46. Reception of intermediate portion38 and leg 40 in groove 34 and recess 36 fixes electrical lead D againstmovement relative to housing 12. Electrical lead D is formed with anotch 48 in which a pointed end 50 of a pivot member E is received. Theother end of pivot member E is formed with a notch 52 receiving a crosspiece 54 of switch arm G. Switch arm G includes downwardly extendingflanges as at 56 to provide stiffness for the switch arm. Switch arm Gincludes an integral deformed portion 58 defining a snapspring havingits end received in notch 60 of electrical lead D. Switch arm G has across piece 62 at its other end on which a valve member 64 is mounted.In this regard, valve member 64 may simply be a conventional switchcontact as found in a double pole single throw switch. Secured beneathcross piece 62 is another electrical contact 66 for cooperating withcontact 32 of electrical lead C. It will readily be seen that anelectrical current path is established through electrical lead D toswitch arm G and electrical contact 66, and also through electrical leadC to electrical contact 32. Wall 14 of housing 12 has another groove 68formed therein and reciprocally receiving an actuating member H which isformed with an enlarged end portion 70 positioned inside cavity 16 sothat the outward reciprocating movement of actuating member H islimited.

Snap spring 58 is deformed as shown in FIG. 1 and normally biases switcharm G to the left in FIG. 1. Switch arm G cannot move to the left in theposition shown because cross piece 54 is engaged with notch 52 of pivotmember E. Pivot member E cannot move because its pointed end 50 isengaged in notch 48 and its other end engages against the bottom 7-4 ofenlarged portion 70 on actuating member H. Snap spring 58 connects withfront cross piece 62 of switch arm G to define a pivot point at 76 andthe engagement of rear cross piece 54 with notch 52 defines a rear pivotpoint. The line connecting these two pivot points is below the point ofengagement of snap spring 58 with notch 60 so that switch arm G is alsobiased downwardly about the rear pivot point to normally hold contact 66in engagement with contact 32. Reciprocating movement of actuatingmember H inwardly deeper into cavity 16 causes pivot member E to pivotupwardly in notch 48 due to engagement of body 74 of enlarged portion 70with the end of pivot member E. This pivotal movement raises notch 52and cross piece 54 until a line connecting notch 52 with pivot point 76is above notch 60. When this occurs, snap spring 58 will be exerting anupward force on cross piece 62 of switch arm G and will cause rapidseparation of contacts 32 and 66 in an upward snap acting movement. Inthis position, notch 48 of pivot member E is still above the lineconnecting notch 52 and pivot point 76 so that snap spring 58 will beexerting a turning moment on switch arm G tending to move notch 52 andcross piece 54 back to its rest position. Thus, releasing actuatingmember H causes switch arm G to snap back to its original position dueto the turning moment moving notch 52 downwardly until the lineconnecting pivot point 76 with notch 52 is below notch 60.

Wall member '14 of housing 12 is formed with an.

arcuate groove 80 which receives a tubular fluid conduit 82. Conduit 82may be formed with, or have secured thereto, shoulder portions 84 and 86positioned respectively on the outside and inside of wall 14 to preventaxial movement of conduit 82. It will be recognized that shoulders suchas 84 and 86 could be eliminated and conduit 82 simply secured inarcuate groove 80 by any suitable adhesive in a well known manner. Fluidconduit 82 includes an outlet opening 90 opening within cavity 16 andhousing 12. The peripheral edge of outlet opening 90 defines a valveseat for cooperation with valve 64 on switch arm G. Air flowing throughoutlet opening 90 is exhausted to atmosphere from cavity 16 through agroove 92 formed in wall 14 of housing 12. It should be recognized thatwhile opening 90 is called an outlet opening it can be either an openingfor exhausting air or for admitting air. That is, conduit 82 can eitherbe a pressure line or a vacuum line.

' With the parts arranged as shown in FIG. 1, an electrical circuit isestablished through lead C, contact 32, contact 66, switch arm G andlead D. Valve member 64 is positioned downwardly away from outletopening 90 so that air can freely flow through outlet opening 90. Axialmovement of actuating member H inwardly deeper into cavity 16 will causea snap acting movement of switch arm G as previously described. Thisrapidly separates contacts 32 and 66 to open the electrical circuit. Atthe same time, valve member 64 snaps upwardly and is shaped to fit insealing engagement with the periphery of outlet opening 90. Thismovement shuts oh the flow of air through conduit 82. Releasingactuating member H will cause a downward snap acting movement of switcharm G to once again bring contacts 32 and 66 into engagement and toseparate valve member 64 from outlet opening 90. It will be understoodby those skilled in the art that such members as housing 12, actuatingmember H and conduit 82 may be made of synthetic plastic material if sodesired. However, other materials may be used as well and materials formno part of the present invention. A suitable cover member may be securedto the top periphery of wall -14 of housing 12 by suitable bolts orrivets passing through holes in the cover aligned with suitable holesand 112 in housing 12.

The pneumatic control arrangement previously described may be used tocontrol a bi-stable fluid amplifier B. A suitable coupling 118 definesan inlet to a flow channel 120 of amplifier B. Coupling 118 may beconnected with a suitable supply of compressed air through a tube 122.Flow channel 120 is divided into two separate outlets 124 and 126 at theother end of amplifier B. Suitable couplings 130 and 132 are connectedwith outlets 124 and 126, and tubes 134 and 136. Flow channel 120 isintersected by a pair of laterally extending flow channels and 142 whichin turn are connected with suitable ..couplings 144 and 146. Coupling146 is connected by a tube 148 to a T 150 having a restricted area 152and a connection 154 to another suitable source of compressed air 156. T150 is connected at its other end with a tube 160 which in turn isconnected to flow conduit 82 leading to housing 12. Coupling 144 may beconnected through a tube 162 to another electro-pneumatic switchingdevice in the same manner as described for coupling 146.

In operation, pressurized air flows from source 156 through line 154 andT 150 to outlet opening 90- in electro-pneumatic switching device A.With the parts arranged as shown in FIG. 1' outlet opening 90 is openand air will be exhausted through groove 92 and wall 14 of housing 12.Restricted portion 152 of T 150 prevents any substantial flow of air tolateral flow channel 142. Pressurized air flowing'through line 122 andcoupling 118 to flow channel 120 in amplifier B may be made to hug the.wall of either outlet opening 124 or 126 due.to theCoanda effect as iswell known in the art of fluidics. For example, with :air'fiowingthrough flow channel 120 and hugging the wall of outlet 126 so. that noair is flowing through outlet 124, electro-pneumatic Switching device Amay be actuated to close outlet opening90 with valve 64 'as previouslydescribed. This blocks oif how of air through outlet opening 90 andcauses air to flow from source 156 past restricted portion 152 and intolateral channel 142. This flow of air'through lateral channel 142 willstrike theair flowing through channel 120 and cause the main air streamto divert or transfer from outlet 126 over to outlet 124. Connection oflateral flow'channel'140 with another electro-pneumatic switching devicemay be used to transfer the main air stream selectivelyfrom flow channeloutlet 124 to 126 in the same manner. As is well known, once the mainair stream is changed from outlet 126 to 124 as described, it willremain flowing through outlet 124 due to the Coanda efiect even thoughoutlet opening 90 is again opened to remove any signal from lateral flowchannel 142. Outlets 124 and 126 of fluid amplifier B may be connectedto suitable pulse processing fluidic circuits in a well known manner. Itwill be understood by those skilled in the art that theelectro-pneumatic switching device of the present' invention could beused in many other vacuum or pressurized pneumatic control systems.

Referring now to FIG. 2, there. is shown a timer assembly J and a timerassembly enclosure K. Details of members J and K may be found withreference to U.S. Pat. No. 3,054,023 to Blecker et al., issued Sept. 11,1962. A suitable timer assembly. may be found in the form of a counterin U.S. Pat. No. 2,735,915 to Hagen, issued Feb. 21, 1957, or U.S. Pat.No. 3,355,602 to Erickson, issued Nov. 28, 1967. The timer mechanism perse forms no part of the present invention. As is well known, hollowrivets may be passed through holes 110 and 112 of housing 12 in FIG. 1to secure the cover onto the housing. When hollow rivets are used screws180 and 182 in FIG. 2 may be passed therethrough and thread intosuitable holes in a mounting bracket M on timer assembly J. A fiat plateY may be secured over switching device A by screws 180 and 182. Plate Ymay include a downwardly projecting tang 184 having a pivot pin 186pivoted thereto. Pivot pin 186 is secured to a lever 188 which extendsbeneath actuating member H of electro-pneumatic switching device A.Lever 188 includes an upwardly extending leg 190 having a sloped orcammed upper edge 192. A rotatable cam or timing wheel on timer assemblyI includes a camming pin 194 which strikes against cam surface 192 onleg 190 at a certain point in the rotational path of cam R. This pivotsthe forward portion of lever 188 downwardly about pivot pin 186 andraises the rear end into contact with actuating member H to open theelectrical circuit and close the outlet opening 90 as previouslydescribed with reference to FIG. 1. This arrangement may be used to selectively open and close electric and pneumatic circuits in anydesirable manner. Also, the electric circuit established throughelectro-pneumatic switching device A may itself control the motor oftimer assembly I. In this manner, the timer may be shut ed at apredetermined time and the pneumatic circuit will be simultaneouslyswitched to a different condition. The rear end of timer assembly Iincludes a plurality of electrical connector pins and only one of whichis referenced by numeral 202. When timer assembly I is inserted intoenclosure K the electrical connector pins as 202 are received insuitable electrical connector sockets as at 204 in the rear of enclosureK. Electrical connections may then be made to the exterior rear ofenclosure K as by connecting wires to screws such as 206 which in turnis connected with socket 204. Conduit 82 of electro-pneumatic switchingdevice A may connect to a tube 208 which in turn is connected with acoupling member 210 as shown in FIG. 8. Coupling member 210 may bethreaded or barbed to receive nuts or spring type push-ons 212 and 214to lock coupling member 210 in opening 216 of rear bracket 218 on timerassembly J. The rear wall of enclosure K may then have a couplingsecured thereto in a manner similar to FIG. 8. Thus, a coupling member220 is held to rear wall 222 of enclosure K by nuts or spring typepush-ons 224 and 226. Coupling member 220 may be shouldered as 230 andhave a suitable elastomeric washer or gasket 232 positionedthereagainst. The inside diameter 234 of coupling member 220 is largeenough to receive end 236 of coupling member 210 and when timer assemblyI is fully positioned within enclosure K, end 236 of coupling 210 willabut and seal against washer 232 in coupling member 220. Pneumatic lineof FIG. 1 may then be connected with coupling 220 of FIG. 2 to establishthe pneumatic circuit.

Referring now to FIG. 6, there is shown a modified form of valve device.The same switch mechanism as described with respect to FIG. 1 may beused in FIG. 6. In this arrangement, a tubular fluid conduit 250 has aninternal flow path 252 through which air may flow. Conduit 250 includesan outlet opening 254 having a valve member S cooperating therewith.Valve member S includes a solid cylindrical shank portion 256 and acircular flat head portion 258. Shank portion 256 is of sufiicientlysmaller diameter than flow path 252 so that valve member S may freelyslide of its own weight with respect to conduit 250. The diameter ofenlarged head portion 258 of valve member S is larger than the diameterof flow path 252 and conduit 250 so that when switch arm G is shifted toits upper position in a manner described with respect to FIG. 1, uppermember 64 on switch arm G will strike head 258 of valve S to seal outletopening 254. When actuating member H is released so that switch arm Greturns to its position establishing an electrical circuit valve memberS falls away from opening 254 of its own weight and also due to pressurein conduit 250. It will be noted that this type of valve arrangement isnot suitable for use when a vacuum pneumatic system is used unless anadditional spring is provided to bias valve S to an open position.

FIG. 7 shows another modified valve arrangement in which conduit 82 isformed with a valve seat 260 to cooperate with a ball 262. In both thisarrangement, and the arrangement of FIG. 6, the valve member is freelypositioned between members 64 on switch arm G and the outlet opening offluid conduit 82, When switch arm G is in its lower position withcontacts 32 and 66 in engagement with one another ball 262 is free ofseat 260 so that flow is established through the outlet opening but ball2-62 is still slightly within the valve seat so that it cannot bedisplaced. In the arrangement of FIG. 7, actuation of actuating member Has described with respect to FIG. 1, moves switch arm G upward andengagement between members 64 and ball 262 forces ball 262 upward intosealing engagement with valve seat 260 to close the outlet opening.Releasing actuating member H moves switch arm G back to its lowerposition and ball 262 drops downward slightly to open the outletopening. In this arrangement, as in FIG. 6, the ball valve may not be asuitable arrangement for use with a vacuum system unless an additionalspring is provided to bias ball 262 away from its seat. An operativearrangement could be provided without a spring if the vacuum wereextremely low and ball 262 were heavy enough to wall away of its ownaccord.

It will be obvious to those skilled in the. art that many other valvingarrangements could be provided. For example, a flapper valve or pinchvalve could also be provided with the outlet opening of conduit 82 beingdefined by a highly flexible elastomeric material. In this manner,member 64 on switch arm G or any other suitable member could be used tosqueeze the tube or close theflapper valve. In addition, it is obviousthat switch arm G could be normally biased to a valve closed position sothat operation of actuating member H would open the valve while closingthe electrical circuit instead of vice versa as described herein. Itwill also be readily apparent that member 64 could be positionedforwardly, rearwardly or to the side of bottom contact 66 in order toclose a valve at the same time that an electrical circuit is establishedbetween contacts 32 and 66. Also, switch arm G could be extended andhave an additional switch contact on its upper surface so that anadditional electrical circuit would be established at the same time thatvalve member 64 closed outlet opening 90. In connection with enclosureK, it will be obvious that a suitable hole, such as 300* in FIG. 4, maybe provided to exhaust air from the electro-pneumatic switch. While theinvention has been described with reference only to certain preferredembodiments, it is obvious that other modifications and alterations thanthose described will occur to others skilled in the art upon a readingand understanding of I this specification.

Having thus described my invention, I claim:

1. In a combined valve and electrical switching device including supportmeans having mounted thereon fixed electrical contact means and movableswitch arm means, said switch arm means 'being movable bet-ween a firstposition in contact with said fixed electrical contact means and asecond position out of contact with said fixed electrical contact means,and actuating means for moving said switch arm means from one of saidpositions to the other of said positions, the improvement comprising:fluid conduit means having an outlet opening in alignment with saidfixed electrical contact means and spaced apart therefrom by an air gapand valve means movable between open and closed positions to selectivelyopen and close said outlet opening, said switch arm means extending intosaid air gap intermediate said outlet opening and said fixed electricalcontact means and cooperating with said valve means for positioning saidvalve means in one of said open and closed positions in one of saidfirst and second positions of said switch arm means and for positioningsaid valve means in the other of said open and closed position-s in theother position of said switch arm means.

2. The device of claim 1 and further including a timer mounted in anenclosure, said device being mounted in said enclosure, and operatingmeans on said timer for moving said actuating means from said first tosaid second position at a predetermined point in the operating cycle ofsaid timer.

3. The device of claim 2 wherein said timer is detachably mounted insaid enclosure and said device is mounted on said timer to be removabletherewith from said enclosure.

4. The device of claim 3 wherein said enclosure has a hole therein forsaid fluid conduit means and further including automatic coupling meansfor connecting and disconnecting said conduit means with said hole whensaid timer is inserted in and removed from said enclosure.

5. A combined valve and electrical switching device comprising: ahousing, a fixed electrical contact secured in said housing, a fluidconduit secured in said housing, said conduit having an outlet openingin alignment with said fixed electrical contact and spaced-aparttherefrom by an air gap, a movable switch arm carried by said housinghaving an end portion which extends into said air gap intermediate saidelectrical contact and said outlet opening, actuating means for movingsaid switch arm from a first position in engagement with said electricalcontact to a second positionout of engagement with said electricalcontact, said switch arm cooperating with said fluid conduit toselectively open and close said outlet opening when said switch arm ismoved between said first and second position.

' References Cited UNITED STATES PATENTS 2,594,216 4/ 1952 Roeser 200*672,540,420 2/ 1951 Bordelon ZOO-61.86 2,735,915 2/1956 Hagen 200-1533,054,023 9/1962 Blecker et al. 3l799 3,091,393 5/1963 Sparrow 1378l.53,162,734 12/1964 v Mansell 20061.86 3,340,896 9/1967 Mon et al.l37--81.5

FOREIGN PATENTS 450,330 8/ 1936 Great Britain.

ROBERT K. SCHAEF'ER, Primary Examiner M. GINSBURG, Assistant Examiner

